BACKGROUND: Pregnancy loss has been associated with myocardial infarction, stroke, and all-cause mortality in women through unknown mechanisms. The aim of this study was to examine these associations in women and their male partners. METHODS AND RESULTS: In this register-based cohort study, all people born between 1957 and 1997, residing in Denmark between 1977 and 2017, and with a registered partner of the opposite sex were eligible for inclusion. Male partners through cohabitation, marriage, or paternity constituted the male cohort. Exposure to pregnancy loss was categorized as follows: 0, 1, 2, or ≥3 pregnancy losses. The outcomes of interest were myocardial infarction, stroke, and all-cause mortality. The Cox proportional hazards model estimated hazard ratios (HRs), adjusted for age, calendar year, parity, and parental history of myocardial infarction or stroke. During follow-up, 1 112 507 women experienced 4463 events of myocardial infarction compared with 13 838 events among 1 120 029 male partners. With the no pregnancy loss group as reference, the adjusted HRs of myocardial infarction in the female cohort after 1, 2, and ≥3 pregnancy losses were as follows: 1.1 (95% CI, 1.0–1.2), 1.3 (95% CI, 1.1–1.5), and 1.4 (95% CI, 1.1–1.8), respectively. In the male partner cohort, the corresponding estimates were 1.0 (95% CI, 1.0–1.1), 1.1 (95% CI, 1.0–1.2), and 1.0 (95% CI, 0.8–1.2), respectively. The outcome of stroke showed similar results. Pregnancy loss was not significantly associated with increased mortality in either sex. CONCLUSIONS: Pregnancy loss or stillbirth was significantly associated with myocardial infarction and stroke in women but not their male partners. Pregnancy loss or stillbirth was not significantly associated with all-cause mortality in women or male partners.